In work that could aid understanding of protein-misfolding diseases, researchers have found that the size of prion aggregates affects their ability to induce further aggregation and cause illness (Science2010,330, 680). The prion hypothesis proposes that aggregates of misfolded infectious prion protein cause conditions such as mad cow disease in cattle and Creutzfeldt-Jakob disease in people by acting as seeds for the transformation of normally folded prion protein into more of the misfolded infectious . . .